Downhole tubular disconnect assemblies

ABSTRACT

Disclosed herein are downhole disconnect assemblies for disconnecting downhole tubulars. Those disconnect assemblies may each include: 1) a housing having an inner surface and a groove disposed in the inner surface; 2) a sub disposed in the housing, the sub having a window aligned with the groove; 3) a locking lug extending through the window and having a projection removably disposed in the groove; 4) a prop sleeve disposed in the sub and releasably coupled to the locking lug; and 5) a load transfer sleeve pushing the housing.

RELATED APPLICATIONS

This application is a continuation-in-part of and claims benefit toco-pending non-provisional application Ser. No. 16/004,036, filed onJun. 8, 2018, which claims benefit to provisional application Ser. No.60/516,670, filed on Jun. 8, 2017; and this application herebyincorporates herein those applications and all amendments thereto as ifset forth herein in their entireties.

BACKGROUND Field of Inventions

The field of this application and any resulting patent is downholetubular disconnect assemblies.

Description of Related Art

Deep well drilling for gas, crude petroleum, minerals, and even water orsteam requires tubes of massive size and wall thickness. Tubular drillstrings may be suspended into a borehole that penetrates the earth'scrust several miles beneath the drilling platform from the earth'ssurface. Situations may arise while drilling where the drill stringbecomes “stuck” deep in the wellbore. Stuck drill strings may resultfrom wellbore cave-in, sloughing, differential pressure sticking,formation swelling, or failure to sufficiently circulate cuttings. Toloosen a stuck drill string, an operator must discontinue drilling andattempt to pull, push, and/or twist the drill string. The operator mayalso run additional tools in the drill string, such as drilling jars, toaugment the loosening process. Such time-consuming operations may causedrilling to overrun budgeted costs.

After unsuccessful attempts to loosen the drill string, the operator maydecide to disconnect the drill string and abandon the stuck portion or“fish” it out afterwards. To disconnect the drill string, the operatorfirst estimates the depth of the “stuck point”. Then, the operatorattempts to disconnect the pipe as close to the stuck point as possibleto retrieve the portion of the drill string above the stuck point.

A hydraulically actuated drill pipe disconnect may be deployed as anintegral part of the drill string at predetermined locations (based onprior drilling history and/or placed in the drill string strategicallyto retrieve expensive hardware like MWD logging instruments). Such adisconnect may be operated, on-command, by pumping an actuating devicedown the drill pipe to engage the disconnect and initiate or actuate therelease. Similarly, the actuating device may be deployed on wireline.

Drilling operations apply severe stress cycles on the bottom holeassembly in a very short time. The drill pipe may rotate from 20 to 1000rpm, thus applying torque to the drill pipe. The stress cycles requiredto induce failure in a tool can be as short as a few hours. One of themost failure-prone components in a drill string is the downholedisconnect assembly, which has multiple points of failure.

One point of failure relates to windows disposed in the body of subs inthe disconnect. Many downhole tubular disconnect assemblies use a set ofrectangular lugs that rest on an internal shoulder in the bottom sub ofthe disconnect as a means of supporting tensile load. The lugs aredisposed in rectangular-shaped windows which are usually machinedradially into the side of the lower sub of the disconnect, or upper sub,depending on design. The shape of these windows tends to represent aproblem because of the stress risers of the corner of the windows.

A second point of failure with many downhole tubular disconnectassemblies is the location of the windows. When the drill string isrotated, the downhole disconnect assembly transmits torque to the lowerdrill pipe so that the drill bit will rotate. Torque is transmittedthrough the downhole disconnect assembly at a torque transmission area.The windows, in which the lugs in the downhole disconnect assembly aredisposed, are frequently located within the torque transmission area.Thus, torque is applied at or through the windows, which increases thepossibility of failure.

During drilling, the lower drill pipe torques up so that the drill bitwill start to cut. When the drill cuts, the torque is momentarilyreleased. Since the cutting operation is not uniform, cycles of cuttingand releasing result in corresponding cycles of torque applicationfollowed by torque release. The chance of failure increases as thenumber of cycles increases.

Often, when drilling a horizontal well, the trajectory of the wellborerequires a significant bend from vertical to horizontal. When the drillstring passes through a severe bend or dogleg, the drill pipe has enoughflexibility to permit the middle of the disconnect to contact one sideof the wellbore, while the top and bottom of the disconnect contact theopposite side of the wellbore. Thus, a bending moment is applied to thedownhole disconnect assembly. This cyclic bending moment varies with therotational speed and applied torque.

The bending stresses are accentuated by the rigidity of the typicaldownhole disconnect assembly, which are usually constructed with outsidediameters larger than the drill pipe, akin to drill collars and threadjointed in close succession.

The torqueing and bending results in stress cycling across the windowwhich can result in a fatigue cracking problem. The present inventionmitigates this problem by locating the windows outside the torquetransmission area.

A third point of failure with existing downhole tubular disconnectassemblies relates to the method of transmitting torque in the tool.Some disconnects, such as that described in U.S. Pat. No. 5,146,984, useinterconnected splines which are machined in the top and bottom subs.Other disconnects use machined fingers that fit into matching notches.Generally, these and other similar disconnects present problems withfretting or fatigue cracking due to the reverse stress cycling loadsthat is inherent to drill string assemblies.

A fourth point of failure with existing downhole tubular disconnectassemblies relates to excessive “play” between lugs, windows and theupper housing portion, which can lead to premature fretting and fatigueof the load bearing components.

A fifth point of failure with downhole tubular disconnect assembliesrelates to stretching of the joint in the tool. High tensile loads,typical to drill string applications, can stretch pipe threaded joints.Effective design of drill pipe joints, called rotary shoulderedconnections (RSC), requires thread makeup sufficient to shoulder thebox/pin joint and pre-load the joint. This pre-load provides that thereis no shoulder separation under the prescribed tensile and bendingmoments. Shoulder separation of the joint under load leads to jointfailure.

For the foregoing reasons, there is a need for a downhole disconnectassembly that reduces applied stresses between components to mitigatefailure of the components and improve tool life.

Various downhole tubular disconnect assemblies and methods fordisconnecting downhole tubular have been proposed and utilized,including some of the methods and structures disclosed in the referencesappearing on the face of this patent. However, those methods andstructures lack the combination of steps and/or features of the methodsand/or structures covered by the patent claims below. Furthermore, it iscontemplated that the methods and/or structures covered by at least someof the claims of this issued patent solve many of the problems thatprior art methods and structures have failed to solve. Also, the methodsand/or structures covered by at least some of the claims of this patenthave benefits that would be surprising and unexpected to a hypotheticalperson of ordinary skill with knowledge of the prior art existing as ofthe filing date of this application.

SUMMARY

Disclosed herein are downhole disconnect assemblies for disconnectingdownhole tubulars, which disconnect assemblies may include: 1) a housinghaving: a) a first inner surface and a first outer surface; b) an uppersocket and a lower socket on the first inner surface; and c) a pluralityof radial grooves formed on the first inner surface between the sockets;2) a window sub having: a) a second inner surface and a second outersurface; b) an upper torque transfer profile and a lower torque transferprofile disposed about the second outer surface for respective slidablemating with the upper and lower sockets on the housing, therebypreventing relative rotation between the window sub and housing; and c)a window defined between the torque transfer profiles therein; 3) alocking lug disposed in the window sub for locking the window sub to thehousing and the sockets, thereby preventing relative longitudinalmovement between the window sub and housing; 4) a prop sleeve fordisengaging the locking lug, thereby allowing for longitudinal movementof the housing relative to the window sub; and 5) a load transfer sleevefor transferring a tensile pre-load to the housing and window sub.

Additionally, disclosed herein are downhole disconnect assemblies fordisconnecting downhole tubulars downhole, which disconnect assembliesmay include: 1) a housing having an inner surface and a groove disposedin the inner surface; 2) a sub disposed in the housing, the sub having awindow aligned with the groove; 3) a locking lug extending through thewindow and having a projection removably disposed in the groove; 4) aprop sleeve disposed in the sub and releasably coupled to the lockinglug; and 5) a load transfer sleeve pushing the housing.

Also, disclosed herein are downhole disconnect assemblies fordisconnecting downhole tubulars downhole, which disconnect assembliesmay include: 1) a housing comprising: a) a first set of socket surfaces;b) a second set of socket surfaces; and c) a groove disposed between thefirst set of socket surfaces and the second set of socket surfaces ofthe housing; 2) a sub disposed in the housing, the sub comprising: a) afirst set of socket surfaces; b) a second set of socket surfaces; and c)a window disposed between the first set of socket surfaces and thesecond set of socket surfaces of the sub; and 3) a locking lug extendedthrough the window into the groove.

Furthermore, disclosed herein are downhole disconnect assemblies fordisconnecting downhole tubulars downhole, which disconnect assembliesmay include: 1) deploying a dart down the downhole tubular string; 2)coupling the dart to a prop sleeve of a tubular disconnect assemblydisposed on the downhole tubular string; 3) pumping a first volume offluid into the downhole tubular string; 4) displacing the prop sleeveaxially; and 5) forcing, with a housing of the tubular disconnectassembly, a locking lug away from the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a profile view of a portion of a downhole tubularstring including a tubular disconnect assembly.

FIG. 1B illustrates a cross-sectional side view of a tubular disconnectassembly in a locked position.

FIG. 2 illustrates an exploded perspective view of a tubular disconnectassembly.

FIG. 3 illustrates a magnified view of a locking lug and a window subhaving a window.

FIG. 4A illustrates a top cross-sectional view of a window sub disposedconcentrically in a disconnect housing, taken on the line A-A and/or B-Bof FIG. 1 looking in the direction of the arrows.

FIG. 4B illustrates a top cross-sectional view of another version of awindow sub disposed in a disconnect housing, taken on the line A-Aand/or B-B of FIG. 1 looking in the direction of the arrows.

FIG. 4C illustrates a magnified view of a portion of a window subdisposed in a disconnect housing, wherein the disconnect housing has aradiused corner.

FIG. 4D illustrates an alternative version of a window sub disposedconcentrically in a disconnect housing, taken on the line A-A and/or B-Bof FIG. 1 looking in the direction of the arrows.

FIG. 4E illustrates a magnified view of a portion of a window subdisposed in a disconnect housing, wherein the windows sub has a windowsocket surface having a plurality of surface portions.

FIG. 5A illustrates a cross-sectional side view of a tubular disconnectassembly in a pre-lock configuration.

FIG. 5B illustrates a cross-sectional side view of a tubular disconnectassembly in a locked configuration.

FIG. 5C illustrates a cross-sectional side view of a tubular disconnectassembly in an actuated configuration.

FIG. 5D illustrates a cross-sectional side view of a tubular disconnectassembly in an unlocked configuration.

FIG. 6A illustrates a cross-sectional side view of a tubular disconnectassembly in a locked configuration receiving a dart.

FIG. 6B illustrates a cross-sectional side view of a tubular disconnectassembly having a dart landed on a prop sleeve.

FIG. 6C illustrates a cross-sectional side view of a tubular disconnectassembly having a prop sleeve slid down a window sub.

FIG. 6D illustrates a cross-sectional side view of a tubular disconnectassembly having locking lugs uncouple from a window sub.

FIG. 6E illustrates a cross-sectional side view of a tubular disconnectassembly having a disconnect housing uncoupled from a window sub.

DETAILED DESCRIPTION 1. Introduction

A detailed description will now be provided. The purpose of thisdetailed description, which includes the drawings, is to satisfy thestatutory requirements of 35 U.S.C. § 112. For example, the detaileddescription includes a description of inventions defined by the claimsand sufficient information that would enable a person having ordinaryskill in the art to make and use the inventions. In the figures, likeelements are generally indicated by like reference numerals regardlessof the view or figure in which the elements appear. The figures areintended to assist the description and to provide a visualrepresentation of certain aspects of the subject matter describedherein. The figures are not all necessarily drawn to scale, nor do theyshow all the structural details, nor do they limit the scope of theclaims.

Each of the appended claims defines a separate invention which, forinfringement purposes, is recognized as including equivalents of thevarious elements or limitations specified in the claims. Depending onthe context, all references below to the “invention” may in some casesrefer to certain specific embodiments only. In other cases, it will berecognized that references to the “invention” will refer to the subjectmatter recited in one or more, but not necessarily all, of the claims.Each of the inventions will now be described in greater detail below,including specific embodiments, versions, and examples, but theinventions are not limited to these specific embodiments, versions, orexamples, which are included to enable a person having ordinary skill inthe art to make and use the inventions when the information in thispatent is combined with available information and technology. Variousterms as used herein are defined below, and the definitions should beadopted when construing the claims that include those terms, except tothe extent a different meaning is given within the specification or inexpress representations to the Patent and Trademark Office (PTO). To theextent a term used in a claim is not defined below or in representationsto the PTO, it should be given the broadest definition persons havingskill in the art have given that term as reflected in at least oneprinted publication, dictionary, or issued patent.

2. Selected Definitions

Certain claims include one or more of the following terms which, as usedherein, are expressly defined below.

The term “abutted against” as used herein is defined as being positionedadjacent to and either physically touching or pressing against, directlyor indirectly. For example, a first object may be abutted against asecond object such that the second object is limited from moving in adirection of the first object.

The term “adjacent” as used herein means next to and includes physicalcontact but does not require physical contact.

The term “aligning” as used herein is a verb that means manufacturing,forming, adjusting, or arranging one or more physical objects into aparticular position. After any aligning takes place, the objects may befully or partially “aligned.” Aligning preferably involves arranging astructure or surface of a structure in linear relation to anotherstructure or surface; for example, such that their borders or perimetersmay share a set of parallel tangential lines. In certain instances, thealigned borders or perimeters may share a similar profile. Additionally,apertures may be aligned, such that a structure or portion of astructure may be extended into and/or through the apertures.

The term “aperture” as used herein is defined as any opening in a solidobject or structure, e.g., disconnect housing, a window sub, a propsleeve, a load transfer sleeve, a housing, a sleeve, or a tubular. Forexample, an aperture may be an opening that begins on one side of asolid object and ends on the other side of the object. An aperture mayalternatively be an opening that does not pass entirely through anobject, but only partially passes through, e.g., as a groove. One ormore grooves may be formed on an outer surface of an object to form pingrooves. One or more grooves may be formed on the inner surface of anobject, e.g., disconnect housing, to form box grooves. An aperture canbe an opening in an object that is completely circumscribed, defined, ordelimited by the object itself. Alternatively, an aperture can be anopening formed when one object is combined with one or more otherobjects or structures. An aperture may receive an object, e.g., a windowsub, a prop sleeve, a load transfer sleeve, a housing, a sleeve, and/ora tubular. For example, a window sub may be received in an aperture of adisconnect housing.

The term “assembly” as used herein is defined as any set of componentsthat have been fully or partially assembled together. A group ofassemblies may be coupled to form a solid housing having an innersurface and an outer surface.

The term “boss” as used herein is defined as a cylindrical protuberanceon a work piece, e.g., a tubular or a shaft. An object may be coupled toa boss of another object. A boss may have a riser face and a tread face,or outer perimeter, that intersects each other to form an angle. Forexample, a prop sleeve may be slid on the tread of a boss of a lockinglug.

The term “connecting surface” as used herein is defined as a surfacethat is coupled to two or more other surfaces. A connecting surface maybe radiused. Accordingly, each connecting surface may also define anarc. A connecting surface may be planar.

The term “coupled” as used herein is defined as directly or indirectlyconnected or attached. A first object may be coupled to a second objectsuch that the first object is positioned at a specific location andorientation with respect to the second object. For example, a tubularmay be coupled to a disconnect housing. A first object may be eitherpermanently, removably, slidably, releasably, shearably, threadably,pivotably, and/or anti-rotatably coupled to a second object. Two objectsmay be “removably coupled” to each other via shear pins, threads, tape,latches, hooks, fasteners, locks, male and female connectors, clips,clamps, knots, and/or surface-to-surface contact. For example, a lockinglug and disconnect housing may be removably coupled to each other suchthat the locking lug may then be uncoupled and removed from a disconnecthousing. Two objects may be “slidably coupled” together, where an inneraperture of one object is capable of receiving a second object. Forexample, a locking lug slid through a window of a window sub may beslidably coupled to the window. Two objects may be “releasably coupled”together, wherein a first object coupled to a second is capable ofmovement after a second object is moved, e.g., slid, rotated, orremoved. For example, a locking lug and a prop sleeve may be releasablycoupled, wherein the locking lug coupled to a prop sleeve can be movedafter the prop sleeve is slid relative to the locking lug. Two objectsmay be “shearably coupled” together, e.g., where a pin is extendedthrough the objects and force applied to one object may break or shearthe pin. For example, a pin may be extended through a prop sleeve and awindow sub, and force applied to the prop sleeve may be transferred tothe pin to cause the pin to be sheared or broken. Additionally, twoobjects may be capable of being “threadably coupled,” e.g., where athreaded outer surface of one object is capable of being engaged with orto a threaded inner surface of another object. Threadably coupledobjects may be removably coupled. Accordingly, a window sub may bethreadably coupled to a tubular where a threaded inner surface, e.g.,box threads or female threads, of the tubular may be engaged with athreaded outer surface, e.g., pin threads or male threads, of the windowsub. Two objects may be “anti-rotatably coupled” together, e.g., wherethe first object may be inhibited from being rotated relative to thesecond object. For example, a window sub may be anti-rotatably coupledto a disconnect housing where the disconnect housing, in some cases, maynot be rotated relative to the window sub. Anti-rotatably coupledobjects may still be moved axially relative to each other.

The term “cylindrical” as used herein is defined as shaped like acylinder, e.g., having straight parallel sides and a circular or oval orelliptical cross-section. Examples of a cylindrical structure or objectmay include a disconnect housing, a window sub, a prop sleeve, a loadtransfer sleeve, a pin, a housing, a sleeve, and a tubular. Acylindrical object may be completely or partially shaped like acylinder. For example, a disconnect housing may have an aperture that isextended through the entire length of a disconnect housing to form ahollow cylinder capable of permitting another object, e.g., a windowsub, a prop sleeve, a load transfer sleeve, a dart, a housing, a sleeve,and/or a tubular, to be extended or passed through. Alternatively, asolid cylindrical object may have an inner surface or outer surfacehaving a diameter that changes abruptly. A cylindrical object may haveand inner or outer surface having a diameter that changes abruptly toform a “lip,” e.g., face, collar, or rim. A cylindrical object may havea collar extending toward or away from the central axis line of theobject. A cylindrical object may have a collar on an inner surface. Acylindrical object may have a collar on an outer surface. Additionally,a cylindrical object, may have a collar that is tapered or radiused.

The term “dart” as used herein is defined as a structure configured toland on another structure, e.g., seat, prop sleeve, or bypass sleeve.Examples of a dart may include a ball, a plug, and a wedge. A dart mayhave a tapered profile. A dart may be elongated. A dart may inhibitfluid flow.

The terms “first” and “second” as used herein merely differentiate twoor more things or actions, and do not signify anything else, includingorder of importance, sequence, etc.

The term “flow path” as used herein is defined as a conduit or spacethrough which fluid is capable of flowing. A flow path may be disposedwithin an object, e.g., a disconnect housing, a window sub, a propsleeve, a load transfer sleeve, a housing, a sleeve, and/or a tubular. Aflow path may extend uninterrupted through ends of an object, e.g., adisconnect housing, a window sub, a prop sleeve, a load transfer sleeve,a housing, a sleeve, and/or a tubular. A flow path may be formed by agroove disposed on an object. A flow path may be a groove disposed in anouter surface of an object. A flow path may be formed by the innersurface of an object. A flow path may be formed by the inner surface ofa group of coupled objects, e.g., a disconnect housing, a window sub, aprop sleeve, a load transfer sleeve, a housing, a sleeve, and/or atubular. A flow path may be formed from two or more connected flowpaths.

The term “flow rate” as used herein is defined as the volume of materialthat passes per unit of time. Volume may be measured in, e.g., gallonsor liters. Time may be measured in, e.g., seconds, minutes, or hours. Aflow rate of a pumped fluid may be measured at the surface. A flow rateof a pumped fluid may be measured before the fluid is pumped into adownhole tubular string. A flow rate of a pumped fluid may be measuredat a station or a pump that pumped the fluid. A “pump down fluid flowrate” may range from as low as 30, 35, 40, 45, 50, 55 gallons per minuteto as high as 60, 70, 80, 90, 120, 160 gallons per minute or higher. An“actuation fluid flow rate” may range from as low as 55, 60, 65 gallonsper minute to as high as 120, 140, 160, 200, 250 gallons per minute orhigher.

The term “fluid” as used herein is defined as material that is capableof flowing. A fluid may be, e.g., a liquid or a gas. Examples of a fluidmay include hydrocarbon, water, drilling fluid, drilling mud, cement,lubricant, cleaning fluid, and motor oil. A fluid can be a mixture oftwo or more fluids. A fluid may absorb heat. A fluid may have propertiessuch as viscosity, anti-foaming, thermal stability, thermalconductivity, and thermal capacity. Fluid in a downhole tubular stringused in driving a motor, e.g., motor, may be call “mud.” A fluid may bewater-based, oil-based, synthetic, or a combination of viscous materialsand solid materials.

The term “fluid port” as used herein is defined as an aperture in astructure for providing ingress and/or egress of fluid therethrough. Afluid port may be disposed in a disconnect housing, a window sub, a propsleeve, a load transfer sleeve, a housing, a sleeve, and/or a tubular. Afluid port may be disposed in a tubular, e.g., housing or sleeve of atubular disconnect assembly or circulating valve assembly. A fluid portmay extend through a shaft assembly. A fluid port may extend in adirection perpendicular to the central axis of a tubular. Fluid portsmay be disposed symmetrically around a tubular. In some cases, fluidports may not necessarily be precisely the same circumferential distanceapart. The preferable circumferential distance between each fluid portin a tubular may be approximately 360 degrees divided by the number offluid ports.

The term “housing” as used herein is defined as a structure, preferablya cylindrical structure, configured to receive therein fluid and/or oneor more objects. Types of housings may include a disconnect housing, awindow sub, a prop sleeve, a load transfer sleeve, a housing, a sleeve,and/or a tubular. A housing may be configured to be filled with fluid,e.g., hydrocarbon, water, drilling fluid, cement, lubricant, and/orcleaning fluid. A housing may have a central aperture extendingtherethrough. A housing may have one or more threaded ends for couplingwith another housing. Multiple housings may be coupled axially to form alonger housing. A housing may receive another object or structuretherein. A housing and an object or structured disposed therein may beconcentric.

The term “locking lug” as used herein is defined as a structure capableof coupling two or more objects together. For example, a locking lug maybe used to couple a window sub and/or a prop sleeve. A locking lug mayinclude two or more surface portions. A locking lug may include two ormore surface portions that defines one or more grooves. A locking lugmay inhibit axial movement of a disconnect housing relative to a windowsub. A locking lug may be disposed in window of a window sub. A lockinglug may have a surface abutted against an object, e.g., prop sleeve. Alocking lug may have teeth or projections. A locking lug may have teethcapable of being coupled to teeth or threads disposed on disconnecthousing. A locking lug may have a portion abutted against threadsdisposed on disconnect housing. A locking lug may have a portion abuttedagainst a radiused surface of a window sub. A locking lug may have aportion abutted against a surface of a prop sleeve.

The term “obround” as used herein is defined as having a shapeconsisting of two semicircles connected by parallel lines tangent totheir endpoints.

The term “pressure” as used herein is defined as force per unit area.Pressure may be exerted against a surface of an object, e.g., pistonhead, sleeve, seat, and/or dart, from the flow of fluid across thesurface.

The term “providing” as used herein is defined as making available,furnishing, supplying, equipping, or causing to be placed in position.

The term “pin” as used herein is defined as a structure capable of beingreceived in an aperture or groove of another structure, e.g., forcoupling two objects or inhibiting movement of an object. A pin may alsobe referred to as a lug. A pin may have a tapered end. A pin may bebroken via dissolving or breaking, e.g., shearing or snapping. A pin maybe broken upon application of threshold force against the pin. A pin maybe used to shearably couple a prop sleeve to a window sub.

The terms “pipe”, “tube”, “tubular” “casing”, “liner” are tubular goodshaving an inner surface and an outer surface and an inner diameter andan outer diameter.

The term “projection” as used herein is defined as a structure and/orprotrusion extending from an object or structure. A projection may bereceived in an aperture, e.g., groove. For example, a locking lug mayhave one or more projections removably disposed in one or more groovesdisposed on a disconnect housing.

The term “pushing” as used herein is a verb that means applying forcee.g., towards and/or against an object or structure, directly orindirectly. Pushing may compel, e.g., urge, cause, influence, force,and/or press, displacement of an object; however, the object may or maynot be displaced. A first object pushing a second object may transferforce to the second object. A first object pushing a second object maycause the second object to push a third object, directly or indirectly.For example, a cap or a tubular pushing a load transfer sleeve may causethe load transfer sleeve to push, directly or indirectly, a housingand/or a window sub. A first object directly pushing a second object mayphysically touch the second object. A first object indirectly pushing asecond object may physically touch a medium that physically touches thesecond object; the medium may be a structure, e.g., washer, spacer, orseal.

The term “radiused” as used herein is defined as having a contour thatis curved, semicircle, and/or hemispherical. Radiused surfaces may beconcave or convex.

The term “seat” as used herein is defined as a structure for receivingan object, e.g., a dart, thereon. A seat may receive a dart. A seat mayhave an inner surface that defines an aperture disposed therethrough. Aseat may have one or more socket surfaces disposed in an inner surfaceof the seat. A prop sleeve may have a landing seat. Multiple seats maybe coupled a downhole tubular or tubular string. Each seat disposedabove a lower seat on a downhole tubular or tubular string may an innersurface having a diameter larger than that of the lower seat.

The term “sleeve” as used herein is defined as a tubular. Types ofsleeves may include a prop sleeve and a load transfer sleeve. The term“prop sleeve” as used herein is defined as a sleeve capable of beingslidably coupled to a locking lug. A prop sleeve may have surfaceportions that can be received in grooves of a locking lug. The term“load transfer sleeve” as used herein is defined as a sleeve capable ofdirectly or indirectly transferring force to a disconnect housing. Aload transfer sleeve may have a first portion, e.g., upper face, abuttedagainst a disconnect housing and a second portion, e.g., a lowershoulder, abutted against a window sub.

The term “slickline” as used herein is defined as a non-conductive cableextendable from surface to a downhole tool.

The term “socket surfaces” as used herein is defined as connectedsurfaces having a polygonal cross-section. An example of a polygonalcross-section may be triangular, square, rectangular, pentagonal,hexagonal, or octagonal. Socket surfaces may have surfaces connected toform a polygonal shape, e.g., triangular, square, rectangular,pentagonal, hexagonal, or octagonal. Males socket surfaces may be on anouter surface of a cylindrical structure, e.g., window sub, sleeve,housing, rod, and/or bolt. Female socket surfaces may be on an innersurface of a cylindrical structure, e.g., disconnect housing, nut,and/or tubular. Female socket surfaces of a disconnect housing arecapable of being aligned with male socket surfaces of a window sub.Female socket surfaces of a disconnect housing are capable of beingabutted against male socket surfaces of a window sub. A window sub or adisconnect housing may have three, four, five, seven, eight, or moresocket surfaces. A window sub or a disconnect housing may have three,four, five, seven, eight, or more connecting surfaces. A window sub mayhave the same number sockets surfaces as that of the number of housingsocket surfaces of a corresponding disconnect housing.

The term “sub” as used herein is defined as a tubular capable of beingdisposed in a housing, a sleeve, or another tubular. A type of a sub mayinclude a window sub.

The term “surface” as used herein is defined as any face of a structure.A surface may also refer to that flat or substantially flat area that isextended radially around a cylinder which may, for example, be part of arotor or bearing assembly. A surface may also refer to that flat orsubstantially flat area that extend radially around a cylindricalstructure or object which may, for example, be part of a landing seat, adisconnect housing, a window sub, a prop sleeve, a load transfer sleeve,a housing, a sleeve, and/or a tubular. A surface may have irregularcontours. A surface may be formed from coupled components, e.g., adisconnect housing, a window sub, a prop sleeve, a load transfer sleeve,a housing, a sleeve, and/or a tubular. Coupled components may formirregular surfaces. A plurality of surfaces may be connected to form apolygonal cross-section. An example of a polygonal cross-section may betriangular, square, rectangular, pentagonal, hexagonal, or octagonal.Socket surfaces may have socket surfaces connected to form a polygonalshape, e.g., triangular, square, rectangular, pentagonal, hexagonal, oroctagonal. Socket surfaces may have curved walls connected to form asubstantially polygonal shape, e.g., triangular, square, rectangular,pentagonal, hexagonal, or octagonal.

The term “tapered” as used herein is defined as becoming progressivelysmaller at one end. Structures that are tapered may have a profile thatis beveled, frustoconical, and/or conical.

The term “threaded” as used herein is defined as having threads. Threadsmay include one or more helical protrusions or grooves on a surface of acylindrical object. Each full rotation of a protrusion or groove arounda threaded surface of the object is referred to herein as a single“thread.” Threads may be disposed on any cylindrical structure or objectincluding a disconnect housing, a window sub, a prop sleeve, a loadtransfer sleeve, a housing, a sleeve, and a tubular. Threads formed onan inner surface of an object may be referred to as “box threads.”Threads formed on an outer surface of an object may be referred to as“pin threads.” A threaded assembly may include a “threaded portion”wherein a section of the threaded assembly includes threads, e.g., pinthreads or box threads. A threaded portion may have a diameter sized toextend through an aperture of a sleeve, a housing, or a collar. Incertain cases, a threaded portion of a first object may be removablycoupled to a threaded portion of a second object.

The term “tubular” as used herein is defined as a structure having aninner surface and an outer surface. A tubular may have an aperturedisposed therethrough. Preferably, a tubular is cylindrical. Examples ofa tubular may a disconnect housing, a window sub, a prop sleeve, a loadtransfer sleeve, a housing, a sleeve, and a tubular. However, any or alltubulars of an assembly may have polygonal cross-sections, e.g.,triangular, rectangular, pentagonal, hexagonal, or octagonal.

The term “tubular disconnect assembly” as used herein is defined as anassembly capable of deployment within a tubular string, e.g., touncouple portions of the tubular string. A tubular disconnect assemblymay be coupled with a landing seat to form a tubular disconnectassembly. A tubular disconnect assembly may include a disconnecthousing, a window sub, a prop sleeve, a load transfer sleeve, a housing,a sleeve, and/or a tubular.

The term “unitary” as used herein defined as having the nature,properties, or characteristics of a single unit. For example, socketsurfaces that are individual parts of a disconnect housing or a windowsub may be unitary in the sense they are not separate but rather areformed from a single piece of material, e.g., plastic, carbon fiber,ceramic, or metal.

The terms “upper,” “lower,” “top,” “bottom” as used herein are relativeterms describing the position of one object, thing, or point positionedin its intended useful position, relative to some other object, thing,or point also positioned in its intended useful position, when theobjects, things, or points are compared to distance from the center ofthe earth. The term “upper” identifies any object or part of aparticular object that is farther away from the center of the earth thansome other object or part of that particular object, when the objectsare positioned in their intended useful positions. The term “lower”identifies any object or part of a particular object that is closer tothe center of the earth than some other object or part of thatparticular object, when the objects are positioned in their intendeduseful positions. For example, a disconnect housing, a window sub, aprop sleeve, a load transfer sleeve, a housing, a sleeve, and/or atubular may each have an upper end and a lower end. Additionally, acylindrical object, e.g., a disconnect housing, a window sub, a propsleeve, a load transfer sleeve, a housing, a sleeve, and/or a tubular,may have an upper portion and a lower portion. The term “top” as usedherein means in the highest position, e.g., farthest from the ground.The term “bottom” as used herein means in the lowest position, e.g.,closest the ground. For example, a cylindrical object, e.g., adisconnect housing, a window sub, a prop sleeve, a load transfer sleeve,a housing, a sleeve, and/or a tubular, may have a top portion and abottom portion.

The term “window” as used herein is defined as an aperture extendingthrough an object, e.g., a window sub.

The term “wireline” as used herein is defined as an electricallyconductive cable extendable from surface to a downhole tool. A wirelinemay also be known as an e-line or smart line.

3. Certain Specific Embodiments

Disclosed herein are downhole disconnect assemblies for disconnectingdownhole tubulars, which disconnect assemblies may include: 1) a housinghaving: a) a first inner surface and a first outer surface; b) an uppersocket and a lower socket on the first inner surface; and c) a pluralityof radial grooves formed on the first inner surface between the sockets;2) a window sub having: a) a second inner surface and a second outersurface; b) an upper torque transfer profile and a lower torque transferprofile disposed about the second outer surface for respective slidablemating with the upper and lower sockets on the housing, therebypreventing relative rotation between the window sub and the housing; andc) a window defined between the torque transfer profiles therein; 3) alocking lug disposed in the window sub for locking the window sub to thehousing and the sockets, thereby preventing relative longitudinalmovement between the window sub and the disconnect housing; 4) a propsleeve for disengaging the locking lug, thereby allowing forlongitudinal movement of the housing relative to the window sub; and 5)a load transfer sleeve for transferring a tensile pre-load to thehousing and window sub.

Additionally, disclosed herein are downhole disconnect assemblies fordisconnecting downhole tubulars downhole, which disconnect assembliesmay include: 1) a housing having an inner surface and a groove disposedin the inner surface; 2) a sub disposed in the housing, the sub having awindow aligned with the groove; 3) a locking lug extending through thewindow and having a projection removably disposed in the groove; 4) aprop sleeve disposed in the sub and releasably coupled to the lockinglug; and 5) a load transfer sleeve pushing the housing.

Also, disclosed herein are downhole disconnect assemblies fordisconnecting downhole tubulars downhole, which disconnect assembliesmay include: 1) a housing comprising: a) a first set of socket surfaces;b) a second set of socket surfaces; and c) a groove disposed between thefirst set of socket surfaces and the second set of socket surfaces ofthe housing; 2) a sub disposed in the housing, the sub comprising: a) afirst set of socket surfaces; b) a second set of socket surfaces; and c)a window disposed between the first set of socket surfaces and thesecond set of socket surfaces of the sub; and 3) a locking lug extendedthrough the window into the groove.

Furthermore, disclosed herein are downhole disconnect assemblies fordisconnecting downhole tubulars downhole, which disconnect assembliesmay include: 1) deploying a dart down the downhole tubular string; 2)coupling the dart to a prop sleeve of a tubular disconnect assemblydisposed on the downhole tubular string; 3) pumping a first volume offluid into the downhole tubular string; 4) displacing the prop sleeveaxially; and 5) forcing, with a housing of the tubular disconnectassembly, a locking lug away from the housing.

In any one of the methods or structures disclosed herein, the loadtransfer sleeve may be abutted against the housing.

In any one of the methods or structures disclosed herein, the loadtransfer sleeve may have a lip pushing the housing.

In any one of the methods or structures disclosed herein, the loadtransfer sleeve may be pushing the sub.

In any one of the methods or structures disclosed herein, the loadtransfer sleeve may be abutted against the sub.

In any one of the methods or structures disclosed herein, a portion ofthe sub may extend through the load transfer sleeve.

In any one of the methods or structures disclosed herein, the loadtransfer sleeve may be disposed around the sub.

In any one of the methods or structures disclosed herein, the window maybe adjacent the groove.

In any one of the methods or structures disclosed herein, a surface ofthe first set of socket surfaces of the housing may be capable of beingabutted against a surface of the first set of socket surfaces of thesub.

In any one of the methods or structures disclosed herein, a surface ofthe second set of socket surfaces of the housing may be capable of beingabutted against a surface of the second set of socket surfaces of thesub.

In any one of the methods or structures disclosed herein, the housingmay further include a socket surface having two surface portions formingan angle less than 180 degrees.

In any one of the methods or structures disclosed herein, the sub mayfurther include a socket surface having two surface portions forming anangle less than 180 degrees.

In any one of the methods or structures disclosed herein, the housingmay further include a radiused connecting surface.

In any one of the methods or structures disclosed herein, the housingmay further include one or more connecting surfaces, wherein none of theconnecting surfaces may be in physical contact with the sub.

In any one of the methods or structures disclosed herein, the lockinglug may have projections coupled to the box threads of the housing.

In any one of the methods or structures disclosed herein, the lockinglug may be capable of sliding in the through the window towards thecentral axis of the window sub.

In any one of the methods or structures disclosed herein, the lockinglug may include a groove for receiving a portion of the prop sleeve.

In any one of the methods or structures disclosed herein, the window submay have a set of window socket surfaces connected to forming a polygon.

In any one of the methods or structures disclosed herein, the propsleeve may be slidably coupled to the window sub.

In any one of the methods or structures disclosed herein, the propsleeve may be shearably coupled to the window sub.

In any one of the methods or structures disclosed herein, the propsleeve may include a groove for receiving a portion of the locking lug.

In any one of the methods or structures disclosed herein, axial forcemay be applied by the load transfer sleeve to the housing.

In any one of the methods or structures disclosed herein, axial forcemay be applied by the housing to the locking lug.

Any one of the methods disclosed herein may further include sliding aportion of the locking lug through a window of a sub.

Any one of the methods disclosed herein may further include receiving aportion of the prop sleeve in a groove disposed in the locking lug.

Any one of the methods disclosed herein may further include receiving aportion of the locking lug in a groove disposed in the prop sleeve.

Any one of the methods disclosed herein may further include abutting ahousing socket surface on the housing against window a socket surface ona sub.

Any one of the methods disclosed herein may further include shearing ashear pin coupled to the prop sleeve and a window sub.

Any one of the methods disclosed herein may further include lifting thedownhole tubular string.

Any one of the methods disclosed herein may further include rotating thedownhole tubular string.

Any one of the methods disclosed herein may further include decouplingthe housing from a window sub.

4. Specific Embodiments in the Drawings

The drawings presented herein are for illustrative purposes only and donot limit the scope of the claims. Rather, the drawings are intended tohelp enable one having ordinary skill in the art to make and use theclaimed inventions.

This section addresses specific versions of downhole tubular disconnectassemblies shown in the drawings, which relate to assemblies, elementsand parts that can be part of a downhole disconnect assembly, andmethods for disconnecting a downhole tubular from another downholeassembly. Although this section focuses on the drawings herein, and thespecific embodiments found in those drawings, parts of this section mayalso have applicability to other embodiments not shown in the drawings.The limitations referenced in this section should not be used to limitthe scope of the claims themselves, which have broader applicability.

Although the methods, structures, elements, and parts described hereinhave been described in detail, it should be understood that variouschanges, substitutions, and alterations can be made without departingfrom the spirit and scope of the invention as defined by the followingclaims. Those skilled in the art may be able to study the preferredembodiments and identify other ways to practice the invention that arenot exactly as described herein. It is the intent of the inventors thatvariations and equivalents of the invention are within the scope of theclaims, while the description, abstract and drawings are not to be usedto limit the scope of the invention. The invention is specificallyintended to be as broad as the claims below and their equivalents.

FIG. 1A illustrates a profile view of a portion of a downhole tubularstring. The portion of the downhole tubular string include a tubulardisconnect assembly 102 disposed thereon. The tubular disconnectassembly 102 may include a disconnect housing 104, a window sub (notshown), a prop sleeve (not shown), locking lugs (not shown), a loadtransfer sleeve 112, an upper cap 114 a, and a lower cap 114 b. Theupper cap 114 a may be coupled to an upper portion of the tubularstring, e.g., a set of tubulars. The lower cap 114 b may be coupled toan upper portion of the tubular string, e.g., a set of tubulars.

In some disconnect assembly versions, caps 114 a, 114 b may be omitted.Instead, a disconnect housing 104 of a tubular disconnect assembly 102may be directly coupled to an upper portion of a tubular string. Inaddition, a window sub 106 of the tubular disconnect assembly 102 may bedirectly coupled to a lower portion of the tubular string.

In any case, together, the upper portion of the tubular string, thetubular disconnect assembly 102, and the lower portion of the tubularstring may be coupled to form a continuous downhole tubular string.

FIG. 1B illustrates a cross-sectional side view of a tubular disconnectassembly 102 in a locked position. The tubular disconnect assembly 102may include a disconnect housing 104, a window sub 106, a prop sleeve108, locking lugs 110 a, 110 b, and a load transfer sleeve 112. Thewindow sub 106 may have a portion disposed concentrically in thedisconnect housing 104. A lower end of the window sub 106 may beextended through a lower end of the disconnect housing 104.

Each locking lug 110 may be slid through a window 208 (FIG. 2 and FIG.3) of the window sub 106. In addition, each locking lug 110 may haveprojections 302 coupled to box grooves 204 disposed in an inner surfaceof the disconnect housing 104. In some cases, when the locking lugs 110a, 10 b are coupled to the box grooves 204, the window sub 106 would beinhibited from axial movement relative to the disconnect housing 104.

The prop sleeve 108 may be disposed concentrically within the window sub106. Also, the prop sleeve 108 may be coupled to the window sub 106 viashear pins 502. The shear pins 502 may be extended through the propsleeve 108 into the window sub 106. Furthermore, the prop sleeve 108 mayhave one or more outer surfaces abutted against the locking lugs 110 a,110 b. Accordingly, in some cases, the prop sleeve 108 may cause thelocking lug 110 a, 110 b to remain coupled to the box grooves 204. Thus,the prop sleeve 108, in some cases, may inhibit the locking lugs 110 a,110 b from being moved towards the central axis of the window sub 106.In other words, the prop sleeve 108, in some cases, may inhibit thelocking lugs 110 a, 110 b from being uncoupled from the box grooves 204.

The load transfer sleeve 112 may be disposed around the lower end of thewindow sub 106. An upper face 510 of the load transfer sleeve 112 may beabutted against a lower face 508 of the disconnect housing 104. In someversions, washers and/or seals may be disposed between the upper face ofthe load transfer sleeve 112 and the lower face of the disconnecthousing 104. Force applied to the washers and/or seals may create atight seal between the disconnect housing 104 and the load transfersleeve 112. Thus, in some cases, the tight seal may inhibit wellborefluid from ingress into the disconnect housing 104.

A portion of the window sub 106 may have pin threads 210 extendedthrough the load transfer sleeve 112. The pin threads 210 may bethreadably coupled to box threads 212 of a lower cap 114 b. In otherversions, the pin threads 210 may be threadably coupled to box threadsof a tubular of lower portion of a tubular string.

FIG. 2 illustrates an exploded perspective view of a tubular disconnectassembly 102. The tubular disconnect assembly 102 may include adisconnect housing 104, window sub 106, a prop sleeve 108, a locking lug110, and a load transfer sleeve 112. The window sub 106 may have one ormore windows 208. Each window 208 may be disposed between a set of upperwindow socket surfaces 206 and a set of lower window socket surfaces206′. In addition, each window 208 may be aligned with the box grooves204 disposed in the disconnect housing 104.

Referring to FIG. 3, a window 208 may extend through a window sub 106.Also, a locking lug 110 is capable of being extended through the window208. Additionally, projections 302 of the locking lug 110 is capable ofbeing slid through the window 208. Also, the locking lug 110 may havefeet 304 a, 304 b capable of being abutted against an inner surface 306of the window sub 106. Accordingly, the feet 304 a, 304 b, in somecases, may inhibit the locking lug 110 from being completely passedthrough the window 208.

In addition, the window 208 may have ends 308 a, 308 b that areradiused, e.g., rounded, curved, semicircle, and/or hemispherical. Also,the locking lug 110 may have ends 310 a, 310 b that are radiused, e.g.,rounded, curved, semicircle, and/or hemispherical. When slid through thewindow 308, the ends 310 a, 310 b of the locking lug 110 would beabutted against the ends 308 a, 308 b of the window 208.

Referring to FIG. 1 and FIG. 2, the disconnect housing 104 may have aninner surface and an outer surface. The disconnect housing 104 may haveon its inner surface a set of upper housing socket surfaces 202, a setof lower housing socket surfaces 202′, and box grooves 204. The boxgrooves 204 may be disposed between the set of housing socket surfaces202 and the set of lower housing socket surfaces 202′.

The window sub 106 may have an inner surface and an outer surface. Thewindow sub 106 may have a set of upper window socket surfaces 206, a setof lower window socket surfaces 206′, and one or more windows 208. Theone or more windows 208 may be disposed between the set of window socketsurfaces 206 and the set of lower window socket surfaces 206′.

When the window sub 106 is disposed in the disconnect housing 104, theset of upper window socket surfaces 206 of the window sub 106 would bealigned with the set of upper housing socket surfaces 202 of thedisconnect housing 104. Additionally, the set of lower window socketsurfaces 206′ of the window sub 106 would be aligned with the set oflower housing socket surfaces 202′ of the disconnect housing 104.

If the disconnect housing 104 were rotated (clockwise orcounterclockwise) relative to the window sub 106, the set of housingsocket surfaces 202, 202′ would respectively be abutted against the setof window socket surfaces 206, 206′. Accordingly, the window sub 106would be inhibited from rotation relative to the disconnect housing 104.

The discussion of FIGS. 4A-E below may apply to the corresponding set ofupper housing socket surfaces 202 and set of upper window socketsurfaces 206 in FIG. 2. Furthermore. the discussion of FIGS. 4A-E belowmay also apply to the corresponding set of lower housing socket surfaces202′ and set of lower window socket surfaces 206′ in FIG. 2.

FIG. 4A illustrates top cross-sectional view of a window sub 106disposed concentrically in a disconnect housing 104. The disconnecthousing 104 may have housing socket surfaces 202 a-f. Each housingsocket surface 202 of the disconnect housing 104 is preferably planar.In addition, the disconnect housing 104 may have housing connectingsurfaces 402 a-f. A housing connecting surface 402 may be connected totwo housing socket surfaces 202. For example, the housing socketsurfaces 202 a, 202 b may be coupled to the housing connecting surface406 b.

The window sub 106 may have window socket surfaces 206 a-f. Also, thewindow sub 106 may have window connecting surfaces 404 a-f. Each windowsocket surface 206 of the window sub 106 is preferably planar. Forexample, the window socket surfaces 206 a, 206 b may be coupled to thewindow connecting surface 404 b.

The window socket surfaces 206 a-f may be aligned with housing socketsurfaces 202 a-f, respectively. Additionally, the window connectingsurfaces 404 a-f may be aligned with the housing connecting surfaces 402a-f, respectively. A window connecting surface 404 may be connected totwo window socket surfaces 206.

When the disconnect housing 104 is rotated relative to the window sub106, portions of the housing socket surfaces 202 would be abuttedagainst portions of the window socket surfaces 206, respectively.Additionally, portions of the housing connecting surfaces 402 would beabutted against portions of the window connecting surfaces 404,respectively.

In some versions, each housing socket surface 206 may be radiused. Inthose versions, each window socket surface 206 may be radiused.

FIG. 4B illustrates a top cross-sectional view of another version of awindow sub 106 disposed in a disconnect housing 104. Window socketsurfaces 206 a-f of the window sub 106 may be respectively aligned withhousing socket surfaces 202 a-f of the disconnect housing 104. Eachhousing socket surface 202 is preferably radiused. Moreover, eachhousing socket surface 202 may be curved inwardly relative to thecentral axis of the disconnect housing 104. In some versions, thehousing socket surface 202 a-f may be planar.

Each pair of housing socket surfaces 204 may be connected to a radiusedconnecting surfaces 402. For example, housing socket surfaces 204 a, 204b may be coupled to ends of a radiused connecting surfaces 402 a. Theradiused connecting surfaces 402 a-f may be equally spaced from oneanother. The radiused connecting surfaces 402 a-f may be spaced at about30, 45, or 60-degree intervals.

The housing socket surfaces 204 a-f and the radiused housing connectingsurfaces 402 a-f may form an aperture in the disconnect housing 104. Theaperture may receive the window socket surfaces 206 a-f of the windowsub 106.

Referring to FIG. 4B and FIG. 4C, each window socket surface 206 ispreferably planar. When the window sub 106 is rotated relative to thehousing 104, the window socket surfaces 206 a-f would be respectivelyabutted against the housing socket surfaces 202 a-f. A portion of eachwindow socket surface 206 is capable of being abutted against a portionof a respective housing socket surface 202. Accordingly, the window subwould be inhibited from further rotation relative to the disconnecthousing 104.

Furthermore, a window corner 406 may be formed by a pair of adjacentwindow socket surfaces 206. For example, the window socket surfaces 206a, 206 b may be coupled, e.g., intersected, to form a window corner 406b. Thus, the window socket surfaces 206 a-f may be connected to form across-section having a shape of a hexagon.

In various versions, the disconnect housing 104 and window sub 106 mayhave corresponding socket surfaces of varying numbers. Thus, the socketsurfaces may form different polygonal cross-sections. Each cross-sectionmay have a shape of a triangle, a square, a rectangle, a pentagon, ahexagon, a heptagon, or an octagon.

Furthermore, each window corner 406 may be disposed adjacent to arespective radiused housing connecting surface 402. However, in somecases, no window corner 406 may be in physical contact with any radiusedhousing connecting surface 402.

FIG. 4D illustrates an alternative version of a window sub 106 disposedconcentrically in a disconnect housing 104. The disconnect housing 104may have housing socket surfaces 202 a-f. Each housing socket surface202 is preferably planar. In addition, the disconnect housing 104 mayhave housing connecting surfaces 402 a-f. Each housing connectingsurface 402 may be planar. Also, each housing connecting surface 402 mayhave a width less than that of a housing socket surface 202. A housingconnecting surface 402 may be connected to two housing socket surfaces202. For example, the housing socket surfaces 202 a, 202 b may becoupled to the housing connecting surface 402 b.

The window sub 106 may have window socket surfaces 206 a-f. The windowsocket surfaces 206 a-f of the window sub 106 may be aligned withhousing socket surfaces 202 a-f of the disconnect housing 104,respectively. Each window socket surface 206 may be planar.Additionally, a window socket surface 206 may be adjacent to a housingsocket surface 202. Also, the window sub 106 may have window connectingsurfaces 404 a-f. Each window connecting surface 404 may be connected totwo window socket surfaces 206. For example, the window socket surfaces206 a, 206 b may be coupled to the window connecting surface 404 b. Eachwindow connecting surface 404 may be adjacent to a housing connectingsurface 402. Each connecting surface 404 may be planar.

Furthermore, each window connecting surface 404 may be disposed adjacentto a respective housing connecting surface 402. However, in some cases,no window connecting surface 404 may be in physical contact with anyhousing connecting surface 402. Moreover, in some cases, no portion ofthe window sub 106 is in physical contact with any housing connectingsurface 402.

When the disconnect housing 104 is rotated relative to the window sub106, portions of the housing socket surfaces 202 would be abuttedagainst portions of the window socket surfaces 206, respectively.

In various versions, the window socket surface 206 a may not be a planarsurface. In those cases, each window socket surface 206 of a window sub106 may be formed from two or more surface portions 408. Referring toFIG. 4E, a window socket surface 206 a may be formed from two windowsocket surface portions 408 a′, 408 a″. The window socket surfaceportions 408 a′, 408 a″ may be connected to form an angle less than 180degrees, e.g., 165, 170, 175, 177, or 178 degrees. The window socketsurface portion 408 a″ is preferably shorter than the socket surfaceportion 408 a′. The window socket surface portion 408 a″ may have alength equal to about 20-30 percent (preferably 26 percent) of acombined length of the window socket surface portions 408 a′, 408 a″.

When the disconnect housing 104 is rotated relative to the window sub106, portions of the housing socket surfaces 202 a, 202 b would beabutted against portions of the window socket surfaces 206 a, 206 b,respectively. For example, as shown in FIG. 4E, the window socketsurface portion 408 a″ may be abutted against a portion of the housingsocket surface 202 a of the tubular disconnect assembly 102.Alternatively, when the window sub is rotated in a clockwise direction,the window socket surface portion 408 a′ would instead be abuttedagainst the housing socket surface 202 a.

Accordingly, torque, e.g., rotational force, imparted to the disconnecthousing 104 may be transferred to the window sub 106. Referring to FIGS.1, 2, and 4D, torque may be transferred via physical contact between theportions of housing socket surfaces 202 a, 202 b and respective ofwindow socket surface portions 408 a, 408 b. However, in some cases,torque is not transferred to portions of the window sub 106 throughwhich a window 208 (FIG. 2) is disposed.

FIG. 5A illustrates a tubular disconnect assembly 102 in a pre-lockconfiguration. The tubular disconnect assembly 102 may include adisconnect housing 104, a window sub 106, a prop sleeve 108, a lockinglug 110, a load transfer sleeve 112, and a lower cap 114 b.

The locking lug 110 may be extended through the window sub 106. Inaddition, the locking lug may have projections 302 coupled to boxgrooves 204 disposed in an inner surface of the disconnect housing 104.In some cases, when the locking lugs 110 a, 110 b are coupled to the boxgrooves 204, the window sub 106 would be inhibited from axial movementrelative to the disconnect housing 104.

The prop sleeve 108 may be disposed concentrically within the window sub106. Also, the prop sleeve 108 may be coupled to the window sub 106 viaa shear pin 502. The shear pin 502 may be extended through the propsleeve 108 into the window sub 106. Furthermore, the prop sleeve 108 mayhave outer surface portions 504 a-d. The outer surface portions 504 b-dmay be respectively abutted against inner surface portions 506 a-c ofthe locking lug 110. The prop sleeve 108 may cause the locking lug 110to remain coupled to the box grooves 204. Accordingly, the prop sleeve108, in some cases, may inhibit the locking lug 110 from being slidtowards the central axis of the window sub 106. In other words, in thepre-lock configuration, the prop sleeve 108 and the locking lug 110 mayinhibit the window sub 106 from being slid axially relative thedisconnect housing 104.

Additionally, the load transfer sleeve 112 may be disposed around thelower end of the window sub 106. An upper face 510 of the load transfersleeve 112 may be abutted against a lower face 508 of the disconnecthousing 104.

In some versions, one or more washers and/or seals may be disposedbetween the upper face 510 of the load transfer sleeve 112 and the lowerface 508 of the disconnect housing 104. However, force may still betransferred from the load transfer sleeve 112 through the one or morewashers and/or seals to the disconnect housing 104.

Still referring to FIG. 5A, in the pre-lock configuration, the windowsub 106 may have a downward-facing shoulder 512 that, in some cases, maynot be in physical contact with an upward-facing shoulder 514 of theload transfer sleeve 112. Thus, a clearance 516 may exist between thedownward-facing shoulder 512 and the upward-facing shoulder 514.

FIG. 5B illustrates a tubular disconnect assembly 102 in a lockedconfiguration. A lower cap 114 b may be coupled to a lower end of thewindow sub 106. The lower cap 114 b may have box threads 212 coupled topin threads 210 of the window sub 106. The box threads 212 may be turnedrelative to the pin threads 210 to cause an upper end of the lower cap114 b to be abutted and/or pushed against a lower end of the loadtransfer sleeve 112. Accordingly, force applied to the lower cap 114 bmay be transferred to the lower shoulder 512 of the window sub 106.Additionally, the force may cause the load transfer sleeve 112 to beabutted against a disconnect housing 104. An upper face 510 of the loadtransfer sleeve 112 may be abutted against a lower face 508 of thedisconnect housing 104. Also, an upward-facing shoulder 514 of the loadtransfer sleeve 112 may be abutted against the downward-facing shoulder512 of the disconnect housing 104. Thus, the force may cause the loadtransfer sleeve 112 to be compressed axially.

FIG. 5C illustrates a tubular disconnect assembly 102 in an actuatedconfiguration. The tubular disconnect assembly 102 may include a propsleeve 108 slid down relative to a disconnect housing 104. The propsleeve 108 may have an inner surface and an outer surface. The outersurface of the prop sleeve 108 may have outer surface portions 504 a-d.The outer surface portions 504 a-d may define grooves 520 a-c of theprop sleeve 108.

The tubular disconnect assembly 102 may also include a locking lug 110.The locking may have inner surface portions 506 a-c. The inner surfaceportions 506 a-c may define grooves 522 a-b. In the actuatedconfiguration, the inner surface portions 504 b-c may be aligned in thegrooves 522 a-b, respectively. Also, the inner surface portions 506 a-cmay be aligned with grooves 520 a-c.

FIG. 5D illustrates a tubular disconnect assembly 102 in an unlockedconfiguration. The tubular disconnect assembly 102 may include a lockinglug 110. The locking lug 110 may have projections 302 uncoupled from boxgrooves 204 dispose in an disconnect housing 104. In addition, thelocking lug 110 may have inner surface portions 506 a-c received ingrooves 520 a-c of a prop sleeve 108, respectively. Conversely, the propsleeve 108 may have outer surface portions 504 b-c disposed in grooves522 a-b, respectively. Thus, in the unlocked configuration, thedisconnect housing 104 may be slid away from the window sub 106.

The views of FIG. 6 illustrate a sequence of disconnecting a downholetubular string via a tubular disconnect assembly 102. An operator mayperform the following steps to disconnect a downhole tubular string,e.g., casing, drill pipe, or liner hanger, that may include the tubulardisconnect assembly 102 coupled thereto. The tubular disconnect assembly102 may be coupled to a portion of the downhole tubular string at thesurface and “tripped” downhole prior to drilling. Moreover, the tubulardisconnect assembly 102 may be in a locked configuration (see FIG. 5A).

As shown in FIG. 5A, in the pre-lock position, a load transfer sleeve112 may be compressed by a cap 114 b threadably coupled to a window sub106. Additionally, box grooves 204 of a disconnect housing 104 mayabutted against projections 302 of a locking lug 110. The locking lug110 may be disposed in a window 208 of the window sub 106. In otherwords, force may be applied to the projections 302 via the box grooves204. The projections 302, in some cases, may not be uncoupled from thebox grooves 204 because outer surfaces 504 b-d of the prop sleeve 108 isabutted against inner surfaces 506 a-c of the locking lug 110.

Referring to FIG. 5A and FIG. 6A, the operator may first deploy, e.g.,drop via freefall or pump in fluid, a dart 220 down the downhole tubularstring. The operator may place the dart 220 into an opening of thedownhole tubular string at the surface. The operator may release thedart 220 without pumping any fluid. Gravity may cause the dart 220 tofall down the downhole tubular string. Preferably, the operator may pumpthe dart 220 in a first volume of fluid down the downhole tubular stringat a pump down fluid flow rate. The dart 220 may be pushed (via thefluid) down the downhole towards disconnect assembly 102.

The first volume of fluid may be as little as 30 barrels, 35 barrels, 40barrels, 45 barrels or as high as 50 barrels, 55 barrels, 60 barrels, 65barrels, 70 barrels or higher. The first volume of fluid may be pumpedat a pump down fluid flow rate.

Referring to FIG. 5B and FIG. 6B, the dart may be landed on a landingseat 218 of a prop sleeve 108. Fluid may flow against the dart 220 andthe landing seat 218. Also, pressure may be exerted on the dart 220and/or the landing seat 218 from the flow of the fluid. However, at thepump down fluid flow rate, the pressure exerted on the dart 220 and/orthe landing seat 218, in some cases, may not be greater than forcerequired to shear, e.g., break or snap, one or more pins 502. Therefore,in some cases, pumped at the pump down fluid flow rate, the fluid maynot push the prop sleeve 108 down.

Consequently, the operator may detect an increase in pressure in thefluid because the flow of the fluid is inhibited by the dart 220 coupledto the prop sleeve 108. Next, the operator may pump a second volume offluid down the downhole tubular string. The second volume of fluid maybe as little as 0.25 barrel, 0.5 barrel, 0.75 barrel, 1 barrel or ashigh as 2 barrels, 3, barrels, 4 barrels, or higher. The second volumeof fluid may be pumped at an actuation fluid flow rate. The actuationfluid flow rate may be less than the pump down fluid flow rate.

The first volume of fluid and second volume of fluid together may exertfluid pressure on the dart 220 and/or landing seat 218 that is greaterthan pressure required to shear, e.g., break or snap, the one or morepins 502. Correspondingly, downward fluid pressure against the dart 220and/or landing seat 218 may cause the prop sleeve 108 to shear the shearpin 502. Accordingly, the shear prop sleeve may be slid down the windowsub 106, as shown in FIG. 6C.

Additionally, one or more ports 602 of the prop sleeve 106, one or moreports 604 of the window sub 106, and one or more ports 606 of a loadtransfer sleeve 112 may be respectively aligned. The fluid may flowthrough the ports 602, 604, 606.

Referring to FIGS. 5C and 6C, outward-facing grooves 520 a-c of the propsleeve 108 may respectively aligned with inner surface portions 506 a-cof a locking lug 110. The locking lug may be disposed in a window 208 ofthe window sub 106. Additionally, inward-facing grooves 522 a, 522 b ofthe locking lug 110 may be respectively aligned with outer surfaceportions 504 b, 504 c the prop sleeve 108. The tubular disconnectassembly 102 is now in an actuated configuration.

Referring to FIG. 5D and FIG. 6D, force transferred from a lower cap 114b, to the load transfer sleeve 112, to the disconnect housing 104 maycause threads 204 of the disconnect housing 104 to push againstprojections 302 of the locking lug 110. The locking lug 110 may be slidaway from the disconnect housing because the outward-facing grooves 520a-c of the prop sleeve 108 may respectively aligned with inner surfaceportions 506 a-c of a locking lug 110 and the inward-facing grooves 522a, 522 b of the locking lug 110 may be respectively aligned with outersurface portions 504 b, 504 c the prop sleeve 108. The tubulardisconnect assembly 102 is now in an unlocked configuration.

Next, referring to FIG. 6E, the operation may pull on the upper portionof the tubular string to uncouple the disconnect housing 104 from thewindow sub 106.

Alternate versions of tubular disconnect assemblies may be described inreference to the views of FIG. 1-6 below.

This disclosure is directed to downhole tubular disconnect assembliesthat may reduce applied stresses between components to mitigate failureof the components. The downhole tubular disconnect assemblies may bedescribed as apparatuses for disconnecting a lower drill string, e.g., adrill collar or a drill pipe, from an upper drill string portion, suchas a length of drill pipe.

The downhole tubular disconnect assemblies may include a disconnecthousing and a locking assembly. The locking assembly further comprises awindow sub, a locking lug, a prop sleeve, and a load transfer sleeve.

The disconnect housing may define a radial grooved surface between apair of polygonal-shaped sockets. The window sub may be positioned inthe disconnect housing and may define a mating torque transfer profilesfor engagement with the sockets of the disconnect housing.

The window sub may define multiple longitudinal windows and circulatingports therein. A locking lug may be disposed in each window of thewindow sub to engage the window. The locking lug may also be extendedpass the window to engage with the grooves in the disconnect housing toprevent the window sub from moving relative to the disconnect housing.The windows in the window sub, along with the lugs disposed therein, maybe spaced between the torque transfer profiles such that any torquetransmitted therebetween is not applied to the windows or lugs.

The prop sleeve may have a plurality of bosses to mate with the internalsurfaces of the locking lugs. The prop sleeve may be shearably securedon a second inner surface of the window sub and has a chamfered internalseat to engage an actuating device, such as a drop ball or dart. Thesleeve may slide downward relative to the window sub to allow the lugsto move radially inward so as to disengage the locking lug from thedisconnect housing, thereby freeing the disconnect housing to axiallymove away from window sub.

The load transfer sleeve may be slidably disposed about the lower end ofthe window sub and contacts the leading face of the disconnect housingto engage the external shoulder of the window sub. Upon threaded makeupwith the lower drill string, the load transfer sleeve may be compressedwhile pre-loading the window sub and disconnect housing to a preferredload as defined by the interference gap. Once pre-loaded, the loadtransfer sleeve may be abutted against the shoulder of the window sub,the RSC can be torqued to the preferred value thus energizing thepre-load of the disconnect joint.

FIGS. 1A-B and FIG. 2 illustrate an assembly of a first embodiment ofthe basic disclosed apparatus components in a downhole drill stringbetween an upper section and a lower section. An expanded description ofeach of these constituent components follows hereafter.

The disconnect housing 104 has a first outer surface and first innersurface defining a central bore therethrough. Upper and lower sockets202, 202′ with a generally hexagonal shape form radially on the firstinner surface of the disconnect housing 104. Moreover, radial grooves204 are formed thereon between the sockets 202, 202′ having a polygonalcross-section.

Referring to FIG. 1B and FIG. 2, a disconnect assembly 102 may include adisconnect housing 104, a window sub 106, a locking lug 110, a propsleeve 108, and a load transfer sleeve 112. A portion of the window sub106 may be disposed concentrically in the

The window sub 106 has a second outer surface and a second innersurface. The second outer surface has upper and lower torque transferprofiles 206, 206′ that respectively mate with the upper and lowersockets 202, 202′ when the locking assembly fully inserts into thedisconnect housing 104 in the running position.

However, persons of ordinary skill in the art will understand that theprinciples described herein with respect to drill collars are applicableto any form or application of pipe or tube.

Returning to FIG. 2, the lower end of the disconnect housing 104 has acentral bore capable of slidably receiving a portion of a lockingassembly. The locking assembly comprises a window sub 106, a locking lug110, a prop sleeve 108, and a load transfer sleeve 112. Description ofthe locking assembly components follows.

Referring to FIG. 2 the window sub 106 has a second outer surface and asecond inner surface. The second outer surface has upper and lowertorque transfer profiles 206 a, 206 b that respectively mate with theupper and lower sockets 202 a, 202 b when the locking assembly fullyinserts into the disconnect housing 104 in the running position.

Referring to FIG. 2 and FIG. 3, a plurality of windows 208 may bedefined and spaced radially in the body of the window sub 106 betweenthe upper and lower torque transfer profiles 202 a, 202 b. Each window208 may be generally elongated with substantially fully radiusedopposite ends and substantially aligns with the radial grooves 204 onthe disconnect housing 104.

A locking lug 110 may be disposed in each window 208. Lug projections302 are formed on the outside edge of the lug 110 which extends radiallyoutwardly from the corresponding window 208. Small feet 304 a, 304 bextend upwardly and downwardly from the inside of each lug 110 and areadapted to fit in a corresponding undercut 518 a, 518 b of the window208 in the window sub 106. Thus, the locking lugs 210 cannot escaperadially outwardly from windows 208, and the maximum radially outwardposition of each locking lug 110.

As pictured in the cross-cut view of FIGS. 4B-C, each socket 202includes six (6) corresponding recesses 402 equally spacedcircumferentially in an inner sidewall of the socket 202. The recesses402 are equally spaced from one another at about sixty (60) degreeintervals circumferentially around the socket 202 so as to receive thecorners of a hexagonally shaped torque transfer profile of the windowsub 106 (illustrated in FIG. 4B). The recesses 402 are dimensioned toprovide for about three (3) degrees of rotation off center of the socket202 with respect to the corners 406 of the window sub 106 in eitherdirection when the corners 406 of the load transfer profile 202 aresubstantially centrally aligned in the recesses 402.

Each socket 202 also includes six (6) longitudinal sidewalls 206 thatextend between and are respectively interconnected by the recesses 402.Referring to FIG. 4C, each of the sidewall 206 may include a firstportion 410 a′ disposed adjacent to a second portion 410 a″ that isangularly displaced with respect to a recess 402 b. The second portion410 a″ extends from the recess 402 b and intersects the first portion410 a′ at an angle. As illustrated in FIG. 4C, the second portion 410 a″may be disposed at an angle (α1) with respect to the first portion 410a′. In other versions, the angle (α1) may be about 2-5 degrees, andpreferably about 3 degrees. The second portion may also have a length(L1) equal to about 20-30 percent of a length of the first portion, andpreferably about 26 percent. The geometry of the socket 202 may providefor a contact point between the sidewalls 202, substantially at anintersection of a second portion 410 a″ with the first portion 410 a′,and a flank 206 a of the torque transfer profile that is away from thecorner 406 b of the torque transfer profile. As illustrated in FIG. 4C,it is to be understood that each end of sidewall 202 intersection aroundthe hexagonal shape may be generally the same and mirrored as describedabove.

An increase in the distance of the contact point away from the corner406 of the window sub 106 increases the surface area and shifts the loadfrom the corner 406 and distributes the stress concentration furtheraway from the corner 406. This may provide for more surface area of thesidewall 202 to contact the torque transfer profile of the window sub106, thereby improving the strength and operable life of the socket 202.This also reduces the risk of the window sub 106 becoming frictionallylocked or stuck in the socket 202 and reduces the risk of the window sub106 being stripped or the socket 202 slipping on the torque transferprofile.

As illustrated in FIGS. 4B-C, the contact point may be a distance (D1)away from the corner 406 b. In some versions, the distance (D1) may beabout 30 to 60 percent of half a length of the flank 206 a (half of thelength between corners 406 a, 406 b) of the torque transfer profile, andpreferably, the distance (D1) is about 45 percent of half the length ofthe sidewall 202 a. It is to be understood that each end of flank 206 aintersection around the hexagonal shape may be generally the same andmirrored as described above.

In other versions, the sockets 202, 202′ may be formed to have differentcross-sectional shapes adapted to mate with different shaped torquetransfer profile, for example, pentagonal, heptagonal, octagonal, doublehexagonal, or other polygonal shapes of the type. The sidewalls 202 andrecesses 402 may be equally spaced circumferentially.

FIG. 4D illustrates a downhole disconnect assembly 102 where eachpolygonal cross-section of the socket 202 and the torque transferprofile have truncated corners 402 instead of the recessed corners 402shown in FIGS. 4B-C. The length of each truncated corner 402 may beshorter than the length of the sidewall 202. Furthermore, the edges(e.g., sidewalls and truncated corners) of the torque transfer profilemay be slightly shorter than the corresponding edges of the socket 202.

The top plan view of FIGS. 4D-E show downhole disconnect assembly 102that may improve the strength and operable life of the socket 202. Asshown in FIG. 4D, each torque transfer profile includes six (6)longitudinal flanks 206 a-f that extend between and are respectivelyinterconnected by truncated corners 402 a-f. Also, each socket 202includes six (6) corresponding corners 406 a-f equally spacedcircumferentially in an inner sidewall of the socket 202.

Referring to FIG. 4E, each of the flanks 206 a-f may include a firstsubstantially straight portion 408 a′ disposed adjacent to secondstraight portion 408 a″ that is angularly displaced with respect to thefirst portion 408 a′. The second portion 408 a″ extends from a truncatedcorner 404 a and intersects the first portion 408 a′ at an angle. Asillustrated in FIG. 4E, the second portion 408 a″ may be disposed at anangle (α1) with respect to the first portion 408 a′. In some versions,the angle (α1) may be about 2-5 degrees, and preferably about 3 degrees.The second portion 408 a″ may also have a length (L1) equal to about20-30 percent of a combined length of the first portion 408 a′ andsecond portion 408″, and preferably about 26 percent. The geometry ofthe torque transfer profile provides for a contact point between theflank 206 a, substantially at an intersection of a second portion 408 a″with the first portion 408 a′, and a sidewall 202 a of the socket 202that may be away from the corner 402 a of the socket 202.

In some versions, the torque transfer profile may be formed to havedifferent cross-sectional shapes adapted to mate with different shapedsockets 202, for example, pentagonal, heptagonal, octagonal, doublehexagonal, or other polygonal shapes of the type. The flanks 206 a-f andtruncated corners 404 a-f may be equally spaced circumferentially.

As illustrated in FIG. 5A, upwardly facing lug shoulders, between thefeet 214 a, 214 b, formed on the inside edge of the locking lug 110define a retaining projection 506 b.

Further, each lug 110 has curved ends 310 (illustrated in FIG. 3)adapted to generally conform to the curved ends 308 in the window 208.Thus, a person skilled in the art may recognize that stressconcentrations are greatly reduced between lugs 210 and windows 208 ascompared to lugs with substantially square ends.

The prop sleeve 108 may be adapted for close sliding engagement with thesecond inner surface of the window sub 106. Downwardly facing propshoulders formed on the outside edge of the prop sleeve 108 definebosses 504 a-d. In the running position, the prop sleeve 108 may bepositioned within the inner bore of the window sub 106 such that theboss 504 b aligns with upper foot 214 a, boss 504 c aligns withretaining projection 210 of the locking lug 110, and boss 504D alignswith lower foot 214 b. The outside surfaces of the bosses 504 b, 504 dabut the inside surface of the feet 214 a, 214 b and retainingprojection 506 b so the lug projections 302 may remain engaged with theradial grooves 204 on the disconnect housing 104, thereby preventingaxial movement of the window sub 106 relative to the disconnect housing104.

One or more shear pins 502 may be attached to window sub 106 and extendsradially into a slot defined in the prop sleeve 108. Thus, the propsleeve 108 may be shearably held in the running configuration.

A threaded joint that may be used in drill string connections that meetsindustry standards is best exemplified as a rotary shouldered connection(RSC). FIG. 5A depicts a cross-sectional view of an assembly having anRSC joint 114 b in a “hand-tight” position, comprising a male threadedpin 210 on the bottom end of the window sub 106 and a female threadedbox 212 of the lower section. The RSC box 212 is shown threaded onto theRSC pin threads 210. When the disclosed apparatus may be assembled in a“hand-tight” position, a physical gap 516 may be present between theinner shoulder 514 of the load transfer sleeve 112 and the externalshoulder 512 of the window sub 106.

Referring to FIG. 5B, the gap 516 may be eliminated by a tensilepre-load imposed upon the locking lug 110, window sub 106, anddisconnect housing 104 sufficient to maintain shoulder contact uponfinal thread makeup of the RSC joint 114 b to the recommended torque. Tomaintain integrity of the drill string, the threaded joints that make upthe drill pipe and drill collars and tools may have to meet loadingcriteria. The joint may provide a leakproof seal and maintainface-to-face contact during the rigors of drilling. Also, the shouldersof the joint may maintain contact under tension and during the cyclicbending that occurs when passing through a dogleg bend in the trajectoryof the wellbore.

FIG. 5B illustrates the disconnect apparatus 102 at an intermediatethread makeup of the RSC joint 114 b. When the RSC threads are inintermediate engagement, the lower end of the disconnect housing 104 andupper end of the load transfer sleeve 112 are in juxtaposition toaxially compress the load transfer sleeve 112 and remove the gap 516.

FIG. 5B illustrates the progression of the RSC to a final makeup at therecommended torque (torque greater than was necessary to shoulder theload transfer sleeve 112 to the window sub 106 in FIG. 5A), which alsopre-loads the RSC such that high tensile and bending loads that occurduring drilling minimizes separation of the joint shoulders.Furthermore, compression of the load transfer sleeve 112 applies atensile pre-load to drive the radial grooves 204 on the disconnecthousing 104 into the locking lug projections 302 and the locking lug 110into contact with the curved upper end of the window 208 in the windowsub 106.

FIGS. 6A-F illustrate operation of the disclosed apparatus if a drillstring becomes stuck, or if it is desired to disconnect the drillstring. The disconnect apparatus 102 may be actuated to release theupper portion of the drill string. A plug 220 may be launched down thedrill string so that the plug may engage a chamfered internal seat 218(illustrated in FIG. 6B) in the lower end of the prop sleeve 108.Hydraulic pressure may be applied in the drill string so that the plug220 and prop sleeve 108 are forced downwardly within window sub 106,shearing shear pins 502. Movement of the prop sleeve 108 causes thebosses 504 b-d to misalign with, and ultimately clear, the feet 214 a,214 b and retaining projection 506 b on the locking lug 110. Continueddownward movement of the prop sleeve 108 releases the locking lug 110 tomove away from the radial grooves 204 on the disconnect housing andinwardly onto the grooves 522 a, 522 b of the locking lug 110.Furthermore, inward movement of the locking lug 110 may be assisted bythe tensile pre-load applied to the disconnect housing 104 anddistributed to the radial grooves 204.

The prop sleeve 108 stops moving once the downwardly facing propshoulders 504 b, 504 c abuts the upwardly facing lug shoulders 506 b,506 c. At this point, an operator may pull on the drill string todisconnect the disconnect housing 104 from the window sub 106 toretrieve the upper drill string portion.

The remaining components may be later retrieved by conventional fishingtools.

What is claimed is:
 1. A downhole tubular disconnect assembly,comprising: a housing having: a first inner surface and a first outersurface; an upper socket and a lower socket on the first inner surface;and a plurality of radial grooves formed on the first inner surfacebetween the sockets; a window sub having: a second inner surface and asecond outer surface; an upper torque transfer profile and a lowertorque transfer profile disposed about the second outer surface forrespective slidable mating with the upper and lower sockets on thehousing, thereby preventing relative rotation between the window sub andthe housing; and a window defined between the torque transfer profilestherein; a locking lug disposed in the window sub for locking the windowsub to the housing and the sockets, thereby preventing relativelongitudinal movement between the window sub and the housing; a propsleeve for disengaging the locking lug, thereby allowing forlongitudinal movement of the housing relative to the window sub; and aload transfer sleeve for transferring a tensile pre-load to the housingand window sub.
 2. The tubular disconnect assembly of claim 1, whereinthe load transfer sleeve is abutted against the housing.
 3. The tubulardisconnect assembly of claim 1, wherein the load transfer sleeve has alip pushing the housing.
 4. The tubular disconnect assembly of claim 1,wherein the load transfer sleeve is pushing the sub.
 5. The tubulardisconnect assembly of claim 1, wherein the load transfer sleeve isabutted against the sub.
 6. The tubular disconnect assembly of claim 1,wherein a portion of the sub extends through the load transfer sleeve.7. The tubular disconnect assembly of claim 1, wherein the load transfersleeve is disposed around the sub.
 8. The tubular disconnect assembly ofclaim 1, wherein the load transfer sleeve axially pushes the housing. 9.The tubular disconnect assembly of claim 1, wherein the housing axiallypushes the locking lug.
 10. A tubular disconnect assembly fordisconnecting a downhole tubular, comprising: a housing comprising: afirst set of socket surfaces; a second set of socket surfaces; and agroove disposed between the first set of socket surfaces and the secondset of socket surfaces of the housing; a sub disposed in the housing,the sub comprising: a first set of socket surfaces; a second set ofsocket surfaces; and a window disposed between the first set of socketsurfaces and the second set of socket surfaces of the sub; and a lockinglug extended through the window into the groove.
 11. The tubulardisconnect assembly of claim 10, wherein the window is adjacent thegroove.
 12. The tubular disconnect assembly of claim 10, wherein asurface of the first set of socket surfaces of the housing is capable ofbeing abutted against a surface of the first set of socket surfaces ofthe sub.
 13. The tubular disconnect assembly of claim 10, wherein asurface of the second set of socket surfaces of the housing is capableof being abutted against a surface of the second set of socket surfacesof the sub.
 14. The tubular disconnect assembly of claim 10, wherein thehousing further comprises a socket surface having two surface portionsforming an angle less than 180 degrees.
 15. The tubular disconnectassembly of claim 10, wherein the sub further comprises a socket surfacehaving two surface portions forming an angle less than 180 degrees. 16.The tubular disconnect assembly of claim 10, wherein the housing furthercomprises a radiused connecting surface.
 17. The tubular disconnectassembly of claim 10, wherein the housing further comprises one or moreconnecting surfaces, wherein none of the connecting surfaces is inphysical contact with the sub.